Fig. 1: ONIX, a unified open-source platform for unencumbered freely moving recordings.

a, Simplified block diagram of the ONI, illustrated via the tetrode headstage: multiple devices all communicate with the host PC over a single micro-coax cable via a serialization protocol, making it possible to design small multi-function headstages. b, The integrated nine-axis absolute orientation sensor and 3D tracking redundantly measure animal rotation, which drives the motorized commutator without the need to measure tether torque, enabling long recording durations. Small drive implants⁴⁴ enable low-profile implants (~20 mm total height). c, The ONIX micro-coax, a 0.31 mm thin tether, compared to standard 12-wire digital tethers. d, Torque exerted on an animal’s head by tethers. Current tethers allow full mobility only in small arenas and in situations when the tether does not pull on the implant, while the ONIX micro-coax applies negligible torque. e, Performance of ONIX: with the 64-channel headstage, a 99.9% worst-case closed-loop latency, from neural voltage reading, to host PC, and back to the headstage (for example to trigger a light-emitting diode (LED)) of <1 ms can be achieved on Windows 10 (see also Extended Data Figs. 6 and 7). FPGA, field-programmable gate array; EIB, electrode interface board; FIFO, first-in first-out buffer.